Air filtration systems utilized in large ventilation systems often employ banks of elongated filtration bags or socks supported by wire filter cage assemblies. The filtration bags are positioned over the filter cages and remove particulates from the air circulated through the bag. The wire filter cages support the bags and prevent the bags from collapsing as air is drawn through the bags. Filter media exclude particulates from passing through the bag along with the air, and the particulates accumulate on the outside of the bags as air is drawn through the bag and filter cage combination.
Wire filter cages supporting filtration bags are commonly used in large-scale filter assemblies. A large-scale filter assembly structure includes a large enclosure. The large enclosure is divided by a horizontal partition plate that separates an upper clean air compartment from a lower dirty air compartment. The partition plate is formed with a large number of openings arranged in a pattern. Each such opening supports a wire filter cage and its associated fabric filter bag. Thus, the air flow passes from the lower dirty air compartment through the suspended filter bags and wire filter cages through the openings in the partition plate and into the upper clean air compartment.
Filter bags are periodically cleaned by shaking or by creating a backflow of air from the inside of the filter bags outward. After an extended period of use it becomes necessary to remove the filter cages and filter bags from the partition plate in order to replace the filter bags. If a one-piece filter cage is employed it is necessary that the upper clean air compartment have sufficient overhead height for the entire length of the filter cage to be accommodated when it is lifted from the horizontal partition plate. Wire filter cages are commonly as long as 26 feet. Some reach lengths of 29 feet. Thus, it is preferred, with lengthy filter cages, that the filter cages be partitioned into two or more sections to allow for a shorter overhead height in the clean air compartment. This shorter overhead height can result in large cost savings in material and construction of large filter assemblies.
Fine dust can form an explosive mixture with air. Air filtration systems are vented to prevent an accumulation of fine dust at a concentration that supports explosive combustion. Larger collector volume requires a greater vent area. A reduction in overhead height and consequently volume in the upper compartment leads to a lower venting cost and associated operating cost.
A variety of techniques have been used to connect multiple sections of wire filter cages. Wire filter cage section connections should be secure and easily assembled and disassembled. In addition, it is desirable that the inner connections be made without leaving any exposed wire ends or other sharp structures. Fabric filter bags are relatively vulnerable to puncture or tearing. If they are snagged on exposed wire ends they may be torn thereby causing particulate leaks and requiring replacement of the bags sooner than would otherwise be necessary.